LAMMPS driver (fix mxl)

Confirm prerequisites

• Build a LAMMPS binary that includes the MaxwellLink fix.
  • Preferred: run mxl_install_lammps to build an lmp_mxl binary.

Configure the socket hub

• Create a TCP or UNIX socket hub on the MaxwellLink (EM) side:
  • hub = mxl.SocketHub(host="0.0.0.0", port=31415, timeout=60.0)

Configure LAMMPS input

• Add the fix to the relevant atom group:
  • fix 1 all mxl <host> <port> [unix] [reset_dipole]

Notes

• Ensure every atom has a charge; otherwise the coupling force is zero.
• Use skills/mxl-hpc-slurm/SKILL.md when the hub and LAMMPS run on different nodes.
• Prefer scaffold template: skills/mxl-project-scaffold/assets/templates/slurm-meep-lammps-tcp
• Common SLURM pattern:
  • Main job writes tcp_host_port_info.txt (host on line 1, port on line 2).
  • Driver job patches a template input and runs LAMMPS:
    • cp in_mxl.lmp in.lmp
    • sed -i -e "s/HOST/$HOST/g" in.lmp && sed -i -e "s/PORT/$PORT/g" in.lmp
    • srun -n $SLURM_NTASKS lmp_mxl -in in.lmp
• Read full details in docs/source/drivers/lammps.rst.